1. Field of the Invention
The invention relates to a safety device for air line lubricators designed for tool maintenance and for giving a signal when the oil in the lubricator bowl falls below a predetermined level. In two known embodiments, the safety device employs a float or a float controlled piston in the lubricator that controls the opening of an air tube which receives air from the lubricator bowl and conveys the air through its outlet end outside of the lubricator to a valve or a signal to be activated. The present invention relates to improvement of the shape of the intake end of the air tube, to a tilting device for unsealing the air tube, and to a coating on the tilting device, or on the float or the float controlled piston for minimizing the effect of vibration on the tube sealing function of the tilting device, the float or float controlled piston.
2. Description of the Prior Art
Applicant's prior U.S. Pat. No. 3805,922, issued Apr. 23, 1974, describes the basic air line lubricator safety device for tool maintenance and for actuating a signal when the oil level in the lubricator falls below a predetermined level; and his pending application, Ser. No. 541,200, now U.S. Pat. No. 3,958,663, issued May 25, 1976, describes a modification of the invention. In both embodiments, an air tube having an inlet opening for receiving compressed air from the lubricator bowl and an outlet opening for conveying the air to a valve or signal outside of the lubricator, is either opened or sealed in response to the movement of the oil level controlled member, namely, a float or a float controlled piston. An expanded range of applications for the use of applicant's described devices has resulted in the improvements disclosed herein.
The prior art teaches an air tube of uniform diameter bore sealed by a sealing member such as a float or a float controlled piston contacting the air intake opening of the tube when the oil level is above a predetermined level. When the oil level in the lubricator drops, the piston or float drops away from the tube opening, thus allowing pressurized air in the lubricator bowl to enter the air tube for its intended functions. However, when heavy oils are used in the lubricator bowl, or when the lubricator and associated equipment are required to employ higher than average air pressure, the described prior art devices do not perform their intended functions as efficiently as they do when light weight oils are used in the lubricator and when average or lower air pressures are required for operation of the mechanism associated with the prior art lubricators. When heavy oils are used in the prior art devices, and a small quantity has worked its way into the tube, the heavy oil clogs the tube due to capillary attraction great enough to prevent passage of the pressurized air from the bowl through the air tube. Further, the use of the lubricator in equipment utilizing higher than average high pressure air increases the attractive force between the air tube inlet end and the sealing member to such a degree that the sealing member (float or float controlled piston) may be held against the tube opening and prevent signal activation even when the oil level in the bowl has dropped below a predetermined level and the safety devices outside of the lubricator should function.